Colin Mathers who leads the Global Burden of Disease group in WHO has confirmed that, in the 2004 GBD, 13.1 per cent of global Daily Adjusted Life Years are attributable to mental or neurological disorders. While the proportions vary very widely from about 10 per cent in low income countries to over 25 per cent in high income countries, it is clear that there is a need for understanding how to address this issue. This volume aims to provide a comprehensive overview of the public health principles of mental and neurological disorders. This vast range of health conditions affects people across the life course, from developmental disabilities in childhood, to schizophrenia and substance abuse in adults, and dementia in old age. Despite this diversity, they all share many features: they are mostly mediated through brain dysfunction or abnormalities, are often chronic in course, typically benefit from multi-component interventions, and are amongst the most neglected conditions in global health. The volume will bring together chapters from the Psychiatry, Neurology, Substance Abuse and Child Development sections of the Encyclopedia of Public Health. The volume will be the first comprehensive text on a public health approach to this diverse group of health conditions and has no obvious competitor. It highlights the common features of many mental and neurological disorders. It provides insights into potential 'cross-over' methods of identification and treatment. It includes chapters on the most frequently diagnosed mental and neurological challenges faced by public health systems.